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FXUS61 KPBZ 211822

Area Forecast Discussion
National Weather Service Pittsburgh PA
222 PM EDT Mon Oct 21 2019

Strong cold front will bring rain and gusty wind overnight into
Tuesday. Breezy conditions will continue under high pressure on
Wednesday, with near seasonal temperature and dry conditions 
expected through Thursday. 


Showers associated with the warm front continue to track north and
east across western OH. While some of the convective allowing models
suggest this will make it into our westernmost zones, the current 
track of precipitation, low-level jet axis, and prevalence of dry 
air should limit measurable precipitation. Thus, PoPs were kept 

The bulk of the rain will arrive with the cold frontal passage, which
is progged to approach eastern OH tonight and western PA early Tues 
morning. Timing with the latest run of models has changed little, so 
the only minor adjustments were made during this time frame. Strong
forcing and climatologically high PWAT values will support an 
efficient period for rainfall which reinforces the categorical PoPs.
Strong warm advection/southerly flow will keep temperatures elevated
overnight, with lows 10-15 degrees above seasonal norms. 


Surface cold front will complete it's passage around midday Tuesday.
High pressure will then build over the region through the latter half
of the day. Subsidence will support mostly sunny conditions, which 
should allow for deep mixing/gusty wind as cold advection continues
both Tuesday and Wednesday. At this time, momentum transfer values
suggest 25-30mph wind gusts will be possible. 

Surface ridging will remain in place on Thursday, though the trough
deepening through the central US will tighten up a baroclinic zone
just west of the region. Temperatures will remain near seasonal


Southwesterly flow ahead of the aforementioned central CONUS trough
will return a narrow band of moisture to the region. Shortwave
passage through the trough may promote surface low development and
precipitation but at this time, the model guidance varies. Generally
stayed in line with ensemble guidance and near seasonal temperature
through the period. 


High confidence forecast save for onset / end time of precip which
could shift +/- 2 hours.  

VFR weather until a cold front inches closer overnight. Rain should
arrive at Zanesville shortly after midnight then take until 10Z until
before it reaches Pittsburgh. Once the rain commences, look for a 
eight hour window of precipitation. For now, given wind speed around
10kts this should keep all airports MVFR at worse for flight 
categories. FKL and DUJ would not shock me to see a brief drop to IFR
CIGS in a heavier shower. 

The front crosses around 11Z in eastern Ohio and 16Z in the 
mountains. Rapid improvement to VFR weather can be expected at the 
tail end of the forecast. 

Wind will be another concern as sustain speeds will be around 12kts
most of the period. Gusts will be in the lower 20kts this afternoon
then again late morning Tuesday. Low level wind shear remains a
concern between 4Z-9Z. Confidence not high enough to include yet, but
given strong low level wind near the surface, something to monitor. 

Wind gusts over 30kts and sustain speeds above 12kts are possible 
Tuesday afternoon through much of Wednesday. No other aviation 
impacts forecast at this time through Saturday.



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